1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device, and particularly relates to a laser processing method for a thin film such as a conductive layer or an insulating layer.
2. Description of the Related Art
Conventionally, a MOS transistor, a thin film transistor, and a semiconductor device including such a transistor is manufactured in such a manner that thin films such as an insulating layer and a conductive layer are formed over a substrate and processed into a desired pattern by a lithography technique. A lithography technique is a technique in which a pattern of a circuit or the like called a photomask, which is formed using a light-blocking material over a transparent flat plate, is transferred to an aimed object by utilizing light. The lithography technique is widely used in a process of manufacturing a semiconductor integrated circuit and the like.
However, the manufacturing process using the lithography technique requires multiple steps such as resist application using a photosensitive resin called a photoresist, pattern light exposure, development, and resist removal. Therefore, as the number of lithography processes is increased, cost is increased and throughput is decreased.
For example, Patent Document 1 (Japanese Published Patent Application No. S63-84789) proposes a technique for forming a linear pattern without using a photoresist. Specifically, a technique is proposed, in which a transparent conductive film (ITO) is linearly irradiated with an excimer laser beam to form a linear opening, so that a pattern is formed.
In Patent Document 2 (Japanese Published Patent Application No. 2000-133636), a method is described, in which two kinds of patterns are formed in a photolithography process by expanding in volume a resist mask that is once used as an etching mask to form an etching mask having a different shape.